| Oceaneering International |
| Ochsner |
| Ochsner Medical Institutions |
| ODECO |
| Odyssey House |
| Offbeat Magazine Publication |
| Office of Human Services |
| Office of Women's services |
| Ogden Corp. |
| Ogden Corporation |
| Oil & Gas Accounting Conference |
| Oil Mop Inc. |
| Oil Spill 2010 |
| Old Arsenal State Commemorative Area |
| Old Louisiana Buildings |
| Old Wildlife & Fisheries Building |
| On Stage |
| One American Corp. |
| One Way Day |
| O'Neill, Charles A. |
| Opelousas, Louisiana |
| Operation Mainstream |
| Operation Upgrade |
| Oplousas, Louisiana "Bienvenue aux Opelousas" |
| Opportunities Industrialization Center |
| Optima Studio |
| Orange Cat News Service |
| Orange Grove Plantation |
| Orchid Society of Jefferson |
| Order of St. Lazarus of Jerusalem |
| Ordre des Arts et Lettres |
| Ordre des Palmes Academiques |
| Organ Historical Society |
| Oriental Collectibles |
| Orleans Area Vocational & Technical School |
| Orleans Audubon Society |
| Orleans Bank & Trust |
| Orleans Club |
| Orleans Levee Board |
| Orleans Parish Board of Assessors |
| Orleans Parish Civil District Court |
| Orleans Parish Civil Sheriff |
| Orleans Parish Civil Sheriff: Deputy Dispatch, 1990-1993 |
| Orleans Parish Civil Sheriff: Deputy Dispatch, 1994 |
| Orleans Parish Civil Sheriff: Reserve Deputy Association |
| Orleans Parish Coastal Zone Management Committee |
| Orleans Parish Conveyance Office |
| Orleans Parish Court of Appeal |
| Orleans Parish Criminal District Court |
| Orleans Parish Criminal Sheriff |
| Orleans Parish Custodian of Voting Machines |
| Orleans Parish Grand Jury |
| Orleans Parish Grand Jury Reports |
| Orleans Parish Jail System |
| Orleans Parish Juvenile Court |
| Orleans Parish Medical Society |
| Orleans Parish Mosquito Control |
| Orleans Parish Public Schools: New Orleans Science & Mathematics High School |
| Orleans Parish Restitution Shelter |
| Orleans Parish Sanitation Services |
| Orleans Parish School Board Advisory Comm. |
| Orleans Parish School Board 19th Century |
| Orleans Parish School Board Organization |
| Orleans Parish School Board: Division of Instruction & Child Advocacy |
| Orleans Parish School Board: Instruction |
| Orleans Parish School Board: Organization |
| Orleans Parish School System |
| Orleans Parish Taxicab Regulations |
| Orleans Parish Voting Districts |
| Orleans Parish Wetlands |
| Orleans Parish Taxicab Regulations |
| Orleans Registrar of Voters |
| Orpheum Theatre. |
| Orthopedic Specialty Association |
| Orton Dyslexia Society |
| Oschner Medical Institutions |
| Oschner Outreach |
| Osiris |
| Other Egypt, The |
| Ouachita & Black Rivers Navigation Project |
| Ouachita Parish, Louisiana |
| Our Kids |
| Our Lady of Holy Cross College |
| Our Lady of Good Counsel |
| Our Lady of the Lake Medical Center |
| Our Lady of the Lake Regional Medical Centre |
| Our Lady of the Oaks Retreat House |
| Our Lady of Wisdom Healthcare Centre |
| Over 40 Baseball League |
| Overture to the Cultural Season |
| Owen's Folksongs 1 |
| Owen, Lydia Hay... |
| Owen, Lyla Hay |
| Oyster Shell Alliance |
| Oysters of Louisiana |
| Oystershell Alliance |
| Ozanam Inn |
| Ozarks Regional Commission |
| Ozone Cmellia Club |